Purse string sutures are used to obtain hemostasis during a variety of surgical procedures. One example is during heart surgery, in which heart tissue is cannulated. A purse string suture is placed in the tissue prior to insertion of a cannula through the suture. The purse string suture is used both to limit bleeding during insertion and to create a hemostatic seal around the cannula after insertion and throughout the procedure.
One procedure in particular in which purse string sutures are used is mitral valve repair. Mitral valve repair can be performed by implanting an adjustable annular implant in the faulty mitral valve, as described in U.S. Pat. No. 7,175,660, incorporated herein by reference. The implant is adjusted for a period following the implantation, to obtain optimal effect. The adjustment is controlled by a detachable adjustment mechanism that may remain extending through the patient's atrium and chest upon closure of the incisions at the end of the implantation procedure. During the post-operative adjustment period, a hemostatic seal must be maintained around the adjustment tool. After the adjustment period, when the tool is detached from the implant and removed from the patient, it may be necessary to re-open the patient's chest to gain access to the atrium to re-establish hemostasis upon removal of the tool. For such a procedure, it would be desirable to provide a device that can be implanted to maintain the seal of a purse string suture around the catheter or adjustment tool during the adjustment period and to tighten the suture to obtain hemostasis when the catheter is removed without the need for further surgical intervention to close the internal incision.
Traditionally, purse string sutures have been tightened using a device such as a choker sleeve, or Romel tourniquet. With such a device, the ends of the suture are threaded through a small sheath and gripped with forceps on the side opposite the suture. The suture ends are then pulled using the forceps while the sleeve is pushed toward the suture loop, until the suture is adequately tight. Alternatively, the suture ends can be wrapped around the sheath, and the sheath then twisted, to tighten the suture. To keep a purse string suture tight around a cannula, for example, the sheath can be taped or otherwise held in place following tightening.
Other types of devices have been developed as alternatives to Romel tourniquets for tightening a purse string suture. One alternative, which can be used during minimally invasive surgery, is a knot-pusher. To use a knot-pusher, after stitching a purse string suture, the ends are tied in a half knot. The half knot is then pushed by the knot pusher toward the suture loop until the suture is adequately tight. For minimally invasive surgery, the knot-pusher can be long and slender for use through a trocar.
U.S. Pat. No. 5,911,728 discloses a purse string suture clamping device for use outside the body, which maintains tightness around a cannula or catheter while in a tissue structure. The clamping device includes a spring through which the ends of the suture extend, and a clamping means secured to the spring on the side opposite the suture. The suture ends are clamped while the spring means is compressed, and the spring then applies a constant tension to maintain a seal around the cannula.
These examples and other purse string suture tightening devices have deficiencies. First, the Romel tourniquet requires direct access to the site being sutured. Further, the tourniquet can not adjust to maintain tension if the suture becomes at all slack. While the knot-pusher requires only minimal access to the site, it does not allow for maintaining tightness after closure of the surgical incision. The knot-pusher also can not adjust to slack in the suture. The purse string suture clamping device is designed for external use with a cannula, not including removal of the cannula, and it is not capable of being implanted.
Therefore, it would be advantageous to provide a new and improved purse string tensioning device that is implantable, and is capable of maintaining the seal of a purse string suture around an elongated medical device and upon removal of the device.